TWI474999B - Process and device for the preparation of phenol from cumene - Google Patents

Description

Method and apparatus for producing phenol

The present invention relates to A method of preparing phenol.

Known by To make phenol. The manufacturing method is carried out in two stages. In the first phase, Oxidized to peroxidation (CHP), the conversion is 20-35 wt%, and in the second stage, CHP is cleaved by acid (typically sulfuric acid) to phenol and acetone. Between the first and second stages, there is usually a concentration step which concentrates the CHP to 70-90% by weight.

At the end of the acid cleavage reaction, which is a large exothermic reaction, the reaction mass is neutralized and the phenol is then recovered by distillation.

Since both the oxidation reaction and the subsequent acid cleavage reaction are accompanied by undesirable secondary reactions, in order to carry out the above two stages of operation, it is necessary to arrange the method/equipment to limit this disadvantage. In particular, it will be produced via a secondary reaction, for example, peroxide II. By-products such as (DCP) and dimethylbenzyl alcohol (DMBA) are selectively converted to phenol and alpha-methylstyrene after downstream processing. The latter will form after the hydrogenation reaction And can be recycled later.

In industry, The oxidation reaction is carried out by a specific reactor (known as "airlift reactor"), which is essentially composed of a cylindrical structure in which a second cylinder is coaxially disposed, the cylinder being An open end that allows the reactant to circulate internally. A second cylinder of this type is known to those skilled in the art and is referred to as a "downcomer". An example of an airlift reactor can be found in Figure 1A, which illustrates the basic unit of such a reactor, including the outer casing, downcomer, and reactants and reaction product feed/discharge points in addition to gas and vapor vents.

Reactive reagent And an oxygen-containing gas, preferably air, is continuously fed to the bottom of the reactor and is also continuously recycled internally through the downcomer. The gas phase consisting essentially of residual air and vapor will follow the reaction product from the top of the reactor (essentially by CHP and unreacted The resulting mixture) and possible by-products are discharged together.

After the CHP is concentrated, the reaction product can be temporarily stored, and then the cleavage reaction is carried out. On an industrial scale, this second reaction is carried out in a closed loop reactor, known in the art as a "loop" reactor. In particular, such a reactor, as shown in Fig. 2, is composed of a tube A having an acid component inlet (1) and an upstream CHP inlet (2) and an acetone inlet (3). In order to increase the overall yield of this process, the addition of acetone plays the role of a moderator, while the acetone is derived from hydroperoxide. One of the two products of the cleavage reaction. The reaction mixture was then quickly introduced into the tube of the tube bundle reactor (B) while the heat of reaction was removed with cooling water flowing through the shell side [via (4) feed and via (5) discharge). The reaction mixture was fed again to tube (A) and this cycle was continued. The phenol produced (along with acetone) is continuously discharged via (6).

The applicant has discovered a A method of making phenol, which is an alternative to the methods known in the art. This new method, in terms of the oxidation stage, improves the CHP selectivity and allows for easier management, for example, it allows for better temperature control and safety. As far as the cleavage reaction is concerned, since the circulation pump has a smaller load to be processed, this method has a lower management cost and has a higher selectivity for phenol and α-methylstyrene.

Therefore, one of the objects of the present invention relates to a method for Hydroperoxide (CHP) A process for the continuous or semi-continuous manufacture of phenols comprising: a. in an airlift reactor Oxidation reaction with an oxygen-containing gas to produce CHP, the air-lift reactor comprising: a1. a cylindrical structure in which the lower half and the upper half of the closed unit are assembled, the unit being respectively configured to feed the reagent and the device a device for discharging a reaction product (substantially CHP), a vapor and an unreacted gas; a2. a second substantially cylindrical structure (downflow tube) opening at the end (bottom) and inside the first structure and Coaxial with the first structure; and a3. an annular gas distributor located at the bottom of the reactor surrounding the second substantially cylindrical structure; characterized in that the downcomer is configured with at least one upper half and/or lower half flared such that The ratio of A1/A2 between the larger cross section A1 and the smaller cross section A2 is between 1.1 and 2; b. Concentrate the CHP-containing solution discharged from the airlift reactor to at least 70 weight %, preferably 80 to 90%; c. in the loop reactor, in the presence of acetone, the phenol is produced by the acid cleavage reaction of CHP, wherein the heat of reaction is two heat exchanges in series in the cycle Recycling; characterized in that the feed of CHP and acetone is in pairs, and each pair It positioned upstream of each switch.

In accordance with the present invention, a schematic representation of an airlift reactor is shown in Figure 1B, in which an innovative component (flare) relative to an older equivalent device is quite apparent, the reactor being supplied with oxygen-rich Air, for example up to 50% by volume. Alternatively, for safety reasons, air can be operated with a reduced oxygen concentration, for example 10-20% by volume. The oxidation reaction occurs between a temperature of 50 to 150 ° C and a pressure of between 0.1 and 0.8 MPa.

The air is supplied by a ring distributor configured with a plurality of holes. The dispenser is located at the bottom of the reactor and allows the supplied air to flow upwards in the form of bubbles that touch the walls of the enclosure. When it reaches the top of the reactor, part of the air is discharged to the outside, and the other part is recycled by liquid transfer and goes down into the downcomer. The flaring of the downcomer is very advantageous for this cyclical movement, which allows the air circulation ratio within the downcomer, which is defined as the ratio between the amount of circulation (volume) and the amount (volume) leaving the reactor, greater than 0.3. Preferably, it is from 0.4 to 0.7, thereby increasing the selectivity of the oxidation reaction.

The downcomer is essentially a tube or cylindrical element placed coaxially inside the reactor, and because it is open at the end (bottom), it allows the reaction The reagent system, in particular air, circulates in a circular downward movement in the central portion of the reactor and moves upwards along the riser of the reactor.

The flare of the downcomer can be located in the upper and/or lower half of the cylindrical element. In both cases, the flare can also start from the bottom and end at the other bottom of the cylindrical element. Preferably, however, the flare begins at about half the length of the tube. For example, the flare preferably involves 10-40% of the length of the tube, starting from one or both bottoms or ends. In both cases, the word flaring refers to the widening of the section of the tube or cylindrical element or downcomer towards the upper and/or lower base.

According to a preferred embodiment of the present invention, the cylindrical ring ring can be joined to the top end of the upper and/or lower half of the downcomer, the height of which depends on the size of the reactor, but can be (for example) in the range of 5 to 100 cm.

According to other embodiments of the invention, The outer casing of the oxidation reactor may also include a similar upward and/or downward flare which substantially corresponds to the flare of the downcomer.

At last, The oxidation reaction is preferably carried out in the presence of a basic compound. Examples of the basic compound are hydroxides and carbonates of an amine, an alkali metal (e.g., lithium, sodium, potassium) or an alkaline earth metal (e.g., calcium and magnesium), which may be used singly or in combination with each other. Such hydroxides and carbonates are typically fed as an aqueous solution/dispersion at a flow rate such that each ton The feed can have from 0.1 to 10, preferably from 0.5 to 8 gram equivalents of an alkali metal. The same concentration is also for amines.

The CHP produced is continuously withdrawn from the airlift reactor and, after concentration, can be stored prior to being sent to the cleavage reaction (semi-continuous process).

The concentration of CHP is carried out by evaporation/distillation in a special apparatus to a concentration higher than 70% by weight. The concentrated product is sent to the production section of the phenol (and acetone is a by-product).

The acid cleavage reaction is carried out in the presence of more acetone and acid, preferably a mineral acid such as sulfuric acid, phosphoric acid or nitric acid. Acetone, which is also a by-product of the acid cleavage reaction, is used for dilution, although this acid is a catalyst that facilitates the cleavage of CHP acid into phenol and acetone (extreme exothermic reaction). The acid is fed to the cycle in a single step.

The concentration of the acid in the reaction medium is in the range of 80 to 250 ppm, preferably 110 to 180 ppm, and more preferably 150 ppm.

Since the acid cleavage reaction of CHP is extremely exothermic, the heat of reaction must be quickly disposed of. To this end, the reactor system comprises two externally cooled tube bundle exchangers. Each tube bundle is located in a container, such as a cylindrical container, in which a cooling fluid (e.g., water) is supplied and is fed and discharged in a continuous flow. These coolants substantially occupy the free volume of the exchanger outside of the tube bundle.

The two exchangers placed in this cycle are in communication with one another such that the outlet of one of them becomes the feed inlet of the other and vice versa.

Feed streams of CHP and acetone are disposed in pairs upstream of each heat exchanger. In particular, the first feed is 0 to 100% CHP and/or acetone, preferably 30 to 70%, more preferably 50%; the second feed pair is relative The feed should be 100 to 0% CHP and/or acetone, preferably 70 to 30%, more preferably 50%.

Figure 3 is a schematic view showing the reaction system for the CHP cleavage reaction of the present invention. The system comprises two tube bundle heat exchangers A1 and B1 connected to each other by a U-tube (80) and a system (70), which comprises a pump which allows the tube to leave the tube bundle (for example in A1) The reaction stream is continuously recirculated to pass it to the subsequent tube bundle (B1). The two tube bundles are contained in a cylindrical vessel with a cooling water circulation inside and are fed and discharged by (40), (50) and (41), (51), respectively.

All acid (10) and partial CHP (11) and acetone (12) feed systems are present in the tubes of system (70), respectively. The second and remaining portions of CHP and acetone are fed to the loop reactor by (20) and (30), respectively.

The reagent mixture is continuously circulated in the loop reactor using a circulation pump. The reaction product (phenol in acetone solution) is continuously discharged from the outlet (60).

According to another embodiment of the loop reactor according to the invention, the acid can be pre-diluted in acetone, in particular in one of the two zone feeds.

1‧‧‧acid ingredient entrance

2‧‧‧CHP entrance

3‧‧‧Acetone inlet

4‧‧‧ Feed inlet

5‧‧‧Drainage

6‧‧‧Drainage

10‧‧‧ Acid inlet

11‧‧‧CHP entrance

12‧‧‧Acetone inlet

20‧‧‧CHP entrance

30‧‧‧Acetone inlet

40‧‧‧ Feed inlet

41‧‧‧Drainage

50‧‧‧ Feed inlet

51‧‧‧Drainage

60‧‧‧Export

70‧‧‧ system

80‧‧‧U-tube

A1‧‧‧tube bundle heat exchanger

B1‧‧‧tube bundle heat exchanger

Figure 1A: Traditional airlift reactor.

Figure 1B: Airlift reactor of the present invention.

Figure 2: Loop reactor.

Fig. 3 is a reaction system for the CHP cleavage reaction of the present invention.

Claims (13)

One for Hydroperoxide (CHP) A method for producing phenol in a continuous or semi-continuous manner, which comprises: a. in an airlift reactor Oxidation reaction with an oxygen-containing gas to produce CHP, and the air-lift reactor comprises: a1. a cylindrical structure in which a lower half and an upper half closed unit are assembled, the unit being respectively configured with a device for feeding a reagent and a device for discharging a reaction product (substantially CHP), a vapor and an unreacted gas; a2. a second substantially cylindrical structure (downflow tube) opening at the end (bottom) and inside the first structure And coaxial with the first structure; and a3. an annular gas distributor located at the bottom of the reactor surrounding the second substantially cylindrical structure; the manufacturing of the CHP is characterized by the upper and/or lower flaring of the downcomer arrangement, The ratio of A1/A2 between the flared larger cross section A1 and the smaller cross section A2 is between 1.1 and 2; b. The CHP-containing solution discharged from the airlift reactor is concentrated to at least 70 % by weight; c in the loop reactor, in the presence of acetone, by the acid cracking reaction of CHP to produce phenol, wherein the heat of reaction is recovered in two heat exchangers connected in series in the cycle; characteristics of the manufacture of phenol The feeds in CHP and acetone are in pairs, and each pair is located in each An upstream of the exchanger. The method of claim 1, wherein the air is supplied to the airlift reactor. The method of claim 2, wherein the air is enriched with up to 50% by volume of oxygen. The method of claim 1, wherein the airlift reactor is supplied with air at a lower oxygen concentration of between 10 and 20% by volume. For example, the method of claim 1 of the patent scope, wherein The oxidation reaction occurs between a temperature of 50 to 150 ° C and a pressure of between 0.1 and 0.8 MPa. The method of claim 1, wherein the cylindrical ring having a height of 5 to 100 cm is joined to the top of the upper and/or lower flaring of the downcomer. For example, the method of claim 1 of the patent scope, wherein The outer casing of the oxidation reactor contains a similar upward and/or downward flare which is substantially equivalent to the flare of the downcomer. The method of claim 1, wherein the air circulation ratio in the downcomer is greater than 0.3, the ratio being defined as the ratio between the amount of circulation and the amount leaving the reactor. For example, the method of claim 1 of the patent scope, wherein The oxidation reaction is carried out in the presence of a basic compound selected from the group consisting of amines and alkali metal or alkaline earth metal hydroxides and carbonates. The method of claim 8, wherein the alkali metal or alkaline earth metal hydroxide and carbonate are supplied in the form of an aqueous solution/dispersion, and the flow rate is such that each ton The feed can have from 0.1 to 10 grams of equivalent alkali metal. The method of claim 1, wherein the CHP is concentrated by evaporation/distillation to a value of from 80 to 90% by weight. The method of claim 1, wherein the acid cleavage reaction occurs in the presence of acetone and an acid selected from the group consisting of sulfuric acid, phosphoric acid or nitric acid. One for Hydroperoxide (CHP) Apparatus for the manufacture of phenols in a continuous or semi-continuous manner, comprising: a. an airlift reactor for CHP synthesis, which consists of: a1. assembling the lower half and the upper half of the closed unit a cylindrical structure, the unit being respectively configured with means for feeding reagents and means for discharging reaction products (substantially CHP), vapor and unreacted gas; a2. second substantial cylindrical structure (downflow) a tube, which is open at the end (bottom) and coaxial inside the first structure and coaxial with the first structure; and a3. an annular gas distributor located at the bottom of the reactor surrounding the second substantially cylindrical structure; wherein, the downflow The tube is provided with an upper half and/or a lower half flare such that the A1/A2 ratio between the flared larger cross section A1 and the smaller cross section A2 is between 1.1 and 2; b. a concentrating device containing a CHP solution discharged from an liter reactor; c. a loop reactor for acid cleavage of CHP in the presence of acetone, which is composed of two heat exchangers arranged in series in a loop It contains two pairs of CHP and acetone feed lines, each pair being located upstream of each exchanger.